The use of microwave energy to cook a variety of foodstuffs to an edible condition is quick and convenient. However, some foodstuffs require crispening or browning to be acceptable for consumption, which is not possible with conventional microwave cooking.
It is known from U.S. Pat. No. 4,641,005 (Seiferth), assigned to James River Corporation, that it is possible to generate thermal energy from a thin metallic film (microwave susceptor) upon exposure thereof to microwave radiation and this effect has been used in a variety of packaging structures to achieve cooking of foodstuffs with microwave energy, including achieving crispening and browning, for example, of pizza crust.
It also has previously been suggested from U.S. Pat. No. 4,230,924 (Brastad et al) to provide microwave energy generated browning of a foodstuff from a food package which includes a flexible wrapping sheet of polymeric film having a flexible metal coating, which either may be relatively thin film or relatively thick foil and which, in either case, is subdivided into a plurality of individual metallic islands in the form of squares.